The ever-increasing demand for smaller sized electrical devices, such as cell phones, digital cameras, tablet computers, personal digital assistants (PDAs), vehicle electronics, etc. has triggered a corresponding need for smaller sized photography modules contained within the device, such as optical imaging lenses, module housing units, image sensors, etc. Size reductions may be achieved from various aspects of the electrical devices, which may include not only the charge coupled device (CCD) and the complementary metal-oxide semiconductor (CMOS), but also the optical imaging lens mounted therein. When reducing the size of the optical imaging lens, however, achieving good optical characteristics may become a challenging problem. Furthermore, achieving a high view angle and a great aperture size are important in certain applications, such as situations where a photography module is used in vehicles.
In light of the above issues, designing an optical imaging lens with a shorter length is not easily achieved by merely decreasing the size of each element proportionally. This is especially true for an optical imaging lens mounted with six lens elements, in which the distance between an object-side surface of the first lens element and an imaging plane along an optical axis may be great. Additionally, factors such as material nature, production difficulty, assembly yield, and so forth are crucial to the application of the design.
Further, the electrical devices may be utilized in various types of environments in which the temperature variation may be high enough to shift the focusing points of the photography modules therein. Therefore, thermal stability is a dominant factor to isolate the focal shift from the change of the temperature. Accordingly, there is a need for optical imaging lenses which are capable of comprising six lens elements therein, with a shorter length, better thermal stability, while also having good optical characteristics.